Hugh Everett III and the Many Worlds Theory
Branching Out of Many Worlds (p/o chapter ten)
Our known universe is defined by two
transformations. In the first all the strange and chaotic futures we might imagine do not happen because of nature's
consistent laws and forces. Primarily gravity, electromagnetism, the strong force, and the weak force, remove from
possibility all of what we would think of as weird or irregular events. The forces of nature create a wonderfully
predictable world where the sun rises and sets each day.
However, if we think about it, we can
reason that there must be many other unique morning and evenings that don't happen here in our own world, and all are
reasonably as possible as the one world we experience. Why don't they exist? Do they exist elsewhere? If we utilize the
same laws and forces of nature, we can conceive of many other paths of time, or many tomorrows, all happening in other
Each one of us who has ever
contemplated the universe has at one time wondered why our one world would exist when all the others as equally possible
never made it to the party. It is when we study quantum mechanics that we find nature acknowledging all those other
worlds that are equal in possibility to our own.
What is imagined as possible by
science, beyond the one world we experience, increased significantly after we discovered that all the small particles
that collectively construct our world travel through space as probability waves. Instead of traveling from point A to
point B like a thrown baseball, today we understand that light behaves in
some ways like a solid particle when it interacts with other particles, however, when light travels from place to place,
like a wave in an ocean it has no definite position. In fact, even matter
particles, such as the particles that make up our bodies, regularly disappear between one position and the next.
The wave nature of light was first
discovered by Thomas Young who noticed that two light beams can shine through each other without the particles colliding
and scattering as they cross paths. This is because two crossing beams of light particles remain wavelike between source
and destination. Young
also recognized that light waves interfere with one another just as sound and water waves interfere. Young produced a
narrow beam of light that passed through a thin divider onto a screen. The divider splits the light beam in half. It
would follow logically that if the beam of light was made from tiny particles then the result should just be two spots
of light on the screen. But Young found the light multiplied into a pattern of light and dark lines, which modern
scientists call an interference pattern.
Below in the split screen experiment
the wave of a single particle passes through two slits, then upon recombining the two waves interfere with one another.
The resulting interference is virtually identical to the interference caused when two waves on the surface of water
interact after they pass through two openings in a wall. The two waves colliding together add up in some places and
cancel in other places.
photon particle travels away from its source purely as a wave of probability.
One of the founders of quantum
theory, Werner Heisenberg discovered what is now a key principle concerning all quantum behavior. As a particle gives up
information about its location, information about its momentum is lost in equal measure. This is called the Heisenberg
uncertainty principle, which states that both the position and momentum of a particle cannot be known. The more we know
about one, the less we know about the other. So as a rule, whenever a particle assumes a precise position in reality, in
that instant it has no momentum. And whenever a particle is moving from one place to another, it has no specific
location. Only when the particle interacts with something else does it then establish which physical reality we will
experience, but in between interactions the particle exists in another type of reality, a sort of multiplicity where all
possibilities are combined together.
Quantum theory was developed near the
turn of the century and it wasn’t until 1957 that all the possibilities within each quantum wave led a young graduate
student of physics named Hugh Everett III to produce the now famous Many-Worlds Theory as his doctorate thesis. Everett
was a student of John Archibald Wheeler, the renowned American physicist and longtime Professor at Princeton. The
Many-Worlds Theory makes the simple conclusion that one probabilistic outcome is as real as any other, predicting an
immense surplus of many-worlds branch away from each moment of now.
We can imagine an infinite number of
copies identical to our present, but then in the next moment, in each copy there is one single particle that is in a
slightly different position than all the others. The denser areas of probability in the interference pattern represent
the more probable worlds, while the thin areas represent the least probable worlds. The areas outside the wave pattern
that are completely dark can be thought of as worlds outside the realm of quantum possibility.
The First transformation
There are two basic transformations
occurring in every moment of every day which are inevitably built into the unfolding of time. In the first
transformation, the majority of bizarre futures one might find in the imaginary stories of science fiction, horror, and
fantasy tales are erased from possibility. This boundary between what is possible and impossible is created by what we
otherwise know as the laws and forces of nature. The forces of nature control and define the areas that matter particles
can move about within. Forces are simply the shapes of probability waves, and those shapes bond particles together, in
groups, in lattices, in symmetries. Once this first transformation is complete there are still many different tomorrows
possible that abide by nature’s rules. We can imagine all sorts of different events that could possibly happen in the
unfolding of each new day. The quantum wave is essentially all the other worlds that are equal in possibility to our
This first transformation is probably
best described by the Sum Over Histories method of mathematically determining the shape of the probability wave, which
was developed by Richard Feynman. Feynman's original highly creative approach doesn’t merely consider the expected
classical paths of particles, it mathematically sums every conceivable path through time and space, even those that
disobey the laws of physics, so a particle zig-zags from left to right, and loop d' loops irregularly in all directions,
irrespective even of past and future. Yet when every conceivable path is considered and the amplitude of each is summed
up, the irregular waves end up canceling one another, while only the expected waves that abide physical laws remain. For
some unknown reason, when all conceivable histories are summed all that remains are the possibilities of everyday life.
Quantum mechanics led physicists such
as David Bohm and John Bell to argue that the wave-particle duality signifies a deep interconnectedness in nature. Where
Bohm developed concepts such as implicate and explicate order to explain the wave particle duality, Bell explained that
no complete explanation of the quantum behavior of particles is possible within what we normally think of as the
physical universe. Bell's theorem argues that quantum mechanics involves a non-local process. In other words, some
non-local process shapes the world we live in.
The Second Transformation
The first transformation eliminates
all the weird or abstract worlds we might find in a horror movie. The second transformation is when the multiplicity of
possible worlds transforms into the single world we live in. We only experience one world at a time. But what causes
this second transformation to happen? Exactly when does it happen? We naturally expect this second transformation occurs
as a solid and definite past rolls into an indeterminate future. Only that isn’t how things work at all. Instead the
past is also a wave of probability.
Nothing reveals the inevitable existence of Many-Worlds more vividly than
the story of Schrödinger's cat. To illustrate how the absurd multiplicity of the quantum wave effects the unfolding of
physical reality, the physicist Erwin Schrödinger created a vivid thought experiment where he places an ordinary cat
within a delicately rigged box. Inside this box there is a radioactive atom that is in a probabilistic state of decay.
The atom has a fifty percent chance of decaying within a short duration of time, a half life, of about five minutes. If
this atom should decay it will expel a single electron particle that will register on a Geiger counter, also inside the
box, and upon detection a hammer will break a glass vile of cyanide gas, instantly killing the cat, that is, if the
particle decays. So the door is shut on this contraption and we wait five minutes.
We know from quantum mechanics that
until we open the box, in the same way the photon travels through both slits, the atom remains in a wave-like state of
multiplicity where after five minutes, in half of all possible worlds it has decayed and in the other half it has
remained stable. In fact, until there is a deterministic outcome which we create by opening the door and observing the
contents of the box, the atom exists in both states simultaneously. Schrödinger pointed out that since the atom remains
in a wave-like state of nothing but probability, as odd as it seems, the wave extends to the Geiger counter inside the
box, which also exists in a wave-like multiplicity of having detected the decay and opened the cyanide in half of all
possible worlds, and having not in the other half, which further means that the seemingly single cat we placed in the
box is somehow simultaneously alive and dead.
Of course this cat-unfriendly
experiment has never taken place, it serves only to scientifically dramatize how quantum mechanics, one of the most
successful theories of science, extends to the larger macrocosmic world of cats and people, and in so doing it forces us
to dramatically change how we imagine the world around us.
The state of the cat can be
interpreted in one of two ways, both of which define reality in dramatic fashion. In the Copenhagen interpretation we
say the decaying atom is in a wave-like state and so is not real, it is just probability, meaning that it has neither
decayed nor remained stable until we open the door of the box. But what about the experience of the cat inside the box?
If the atom somehow isn’t real when wave-like, then the cat isn’t real either, it’s neither dead nor alive. But is
this idea acceptable? It is one thing to imagine a particle isn’t real if a human being isn’t observing it, and
another to imagine a cat needs to be observed.
Believe it or not, there are some who
egocentrically claim that only humans can create reality. The Copenhagen interpretation led one physicist to remark that
the moon doesn’t exist when no one is looking at it. Of course if someone is arrogant enough to claim that the cat’s
observations aren't independently real, the next hypothetical step would be to place that person in the box and start
the experiment over.
In the Many-Worlds version of
Schrödinger’s cat we don't try to avoid the idea that beyond our vision two realities exist simultaneously, so we say
the particle has decayed in one reality, and remained stable in the other reality, and two superimposed conflicting
realities exist. But neither reality is yet connected in a definite way to an observer standing outside the box. Instead
the experiment has created two cats, one is dead and one is alive. Then when we open the box to observe the dead or
alive cat we collapse the wave and connect ourselves to one of the two realities. Note however something that is really
strange here. The outside world as we open the door to observe the cat, and so we ourselves, split into two principle
realities. In one we exist observing the cat alive and in another we exist observing the cat as dead. What this means is
that we split into two different realities in the future because behind the door there are two different pasts.
Quantum mechanics doesn’t merely
reveal that time is branching away from the present. It reveals that the past is often just as indeterminate as the
future. As physicist Thomas Hertog states, “Quantum mechanics forbids a single history”. This brings the infinite so
much closer than even an imaginative person is comfortable with. What is perhaps the most startling consequence of
discovering quantum mechanics, is realizing that everything beyond our observations exists in a state of multiplicity.
When we imagine the future we usually
see it as potential. Some people state that anything can happen although we don’t expect much of anything will happen,
we expect the ordinary, but we at least imagine that the varied possibilities of the future grow greater with a greater
period of time. What might happen tomorrow is rather limited compared to what all might happen in a year or a decade.
But we think the infinite possibilities are out there in the future. As it turns out, the past is also probabilistic.
Quantum mechanics suggests that anything we haven’t yet observed, everything happening in another state or country,
everything happening a mile away, literally everything in the world beyond our five senses, is in a quantum state of
multiplicity. The infinite isn’t out there in the distant future. It is just on the other side of any door. It is just
beyond our vision, our hearing, our touch, our smell. It is everything we don’t know. If we haven’t yet read the
news of the day, all the possible newsworthy events are happening simultaneously in alternative universes waiting for us
to turn each page of the newspaper, and only then do we connect with one of those worlds.
Some scientists shrug at the
Many-Worlds Theory and continue to believe there is something that makes quantum reality operate only at the subatomic
level, and not at a macrocosmic level where we live. But the technological applications of quantum mechanics to
chemistry and electronics have already had a tremendous impact upon society. In addition to television shows and movies
where characters cross over into parallel universes, physicists are working toward a complete quantum description of
reality. If a complete theory is ever accomplished, it will explain why certain things are possible while others are
less so, and it will tell us what is impossible. Presently, the Many-Worlds Theory does not claim that other worlds with
different laws and forces of nature cannot exist, but if the probabilities of quantum mechanics were found to be basic
to nature then we would reasonably conclude the same laws govern all of existence.
Lots more about the Timeless Infinite Universe at:
essay last updated Mar 16th, 2007